As the video signal processing speed has become faster, a solution for encoding/decoding ultra high definition (UHD) video is being developed. A solution for processing UHD video as well as HD video without any problem, when receiving the UHD video by using a legacy (or conventional) HD receiver, is being developed. For example in case an aspect ratio of a video that is being transmitted is different from an aspect ratio of a display device of a receiver, each receiver shall be capable of processing the corresponding video at an aspect ratio best-fitting the display device.
However, in case of a related art device decoding is not supported for a compressed video having a 21:9 format, which corresponds to the aspect ratio of a UHD video. In case a video of 21:9 is being transmitted, a receiver having the aspect ratio of 21:9 is required to directly process and display the video of 21:9, and a receiver having the aspect ratio of 16:9 is required to first receive a video stream having the aspect ratio of 21:9 and then output the received video stream in a letterbox format, or required to first receive a cropped video having the aspect ratio of 16:9 and then output a video signal. Additionally, in case subtitles are included in the stream, the receiver having the aspect ratio of 16:9 shall be capable of processing subtitle information.
As described above, since the aspect ratio of a legacy HD receiver or a receiver that can process UHD video can be different, in case the corresponding video is transmitted or received and then processes, a problem may occur.